Bryan Cranston
Dalton Trumbo

Diane Lane
Cleo Trumbo

Helen Mirren
Hedda Hopper

Elle Fanning
Nikola Trumbo

Louis C.K.
Arlen Hird

John Goodman
Frank King

Michael Stuhlbarg
Edward G. Robinson

David James Elliott
John Wayne

Roger Bart
Buddy Ross

Mark Harelik
Ed Muhl

John Getz
Sam Wood

Alan Tudyk
Ian McLellan Hunter

James DuMont
J. Parnell Thomas

Richard Portnow
Louis B. Mayer

Adewale Akinnuoye-Agbaje
Virgil Brooks

Stephen Root
Hymie King

Dean O'Gorman
Kirk Douglas

Garrett Hines
Andrew Hird

Christian Berkel
Otto Preminger

Dan Bakkedahl
Roy Brewer

Toby Nichols
Chris Trumbo (age 6-10) (as Tobias McDowell Nichols)

Dalton Trumbo
Himself (archive footage)

Laura Flannery
Party Goer

Madison Wolfe
Niki Trumbo (age 8-11)

Johnny Sneed
Robert Stripling

Rio Hackford
Reporter

Dane Rhodes
Reporter

Peter MacKenzie
Robert Kenny

John Neisler
Jury Foreman

Sean Bridgers
Jeff Krandall

Meghan Wolfe
Mitzi Trumbo (age 6-8)

Mark Harelik
Edward 'Ed' Muhl

Suzanne LaChasse
Showgirl (uncredited)

Rhonda Laizer
Trumbo Friend (uncredited)